Re: Another possible gb.poppler bug?

[gbWilly <gbWilly@xxxxxxxxxxxxxx>]

On Tuesday, December 2nd, 2025 at 17:25, Lee <t.lee.davidson@xxxxxxxxx> wrote:

> On 12/2/25 10:55 AM, gbWilly wrote:
> 
> > So, in other pdfviewers they are fully rendered during the opening the file.
> 
> 
> Not necessarily. As I reported in another message, one particular PDF I viewed with Okular did not render the thumbnail until it
> was scrolled into view.
> 
> > Now, I can play a bit with when I render, to ensure the document is shown, before starting rendering the thumbs. But during rendering, even a timer object doesn't trigger, as the whole application seems to be caught up in the rendering. So showing the document first, gives some visible comfort to the user, but you can't do shit until the rendering is finished.
> 
> 
> You could determine if the document has embedded thumbnails, when it is loaded, by testing if a thumbnail for the first page is
> found.

The application AND example I posted already do that and always load the embedded thumbs if existing (very fast).
I have about 10 different test pdf files, only a few have embedded thumbnails, and as Claus explained, this seems to be the norm. (He convinced me together with your pdf online checks for internal thumbnails). So, that discussion is done and I already moved on to work on load improvements.

>If thumbnails are not embedded and self-rendering is needed, you could:
> 
> Load up a generic, lightweight thumbnail for each page and then use IconView's Draw event to render an appropriate thumbnail, or
> Use Tasks to generate the thumbnails.

If I render them at 4 dpi it still takes a while. It seems like I have to do it in chunks somehow, but during the rendering the application in non reactive!

I tried loading pdf first, so no rendering, just load the document with an empty IconView (very fast). Then, and no sooner I started the rendering. If I meanwhile scroll down in the document it doesn't react until the rendering has finished. I also tried a timer to measure loading times.

I start the timer before the For Next loop where the rendering occurs, and stop it right after the loop. The timer interval is 1 sec and I increment a time value that starts at 00:00:00. The Timer isn't even triggered and thus returns same 00:00:00 value when stopped at the end of the loop. I can count out loud 3 seconds before I see thumbnails, timer says 0 seconds. So, the rendering makes that nothing reacts until it is done.

Maybe TASKS, as you suggest, could help so it runs as a background process not interfering with the user. Then when opening a pdf file only render the first 10 or so thumbs for showing and do the rest somhow in background as a task.

Thanks for the ideas and suggestions,

gbWilly